The present invention relates to a device for fastening an object against a wall or the like, as a plug-in mounting.
Such devices generally have an externally threaded bolt onto one end of which a nut is threaded and onto the other end of which an expander element is mounted. The end on which the expander element is mounted is at least partially conical, the maximum diameter of which is at most equal to the diameter of the bolt. The expander element comprises two half-shell-like parts held in a displaceable manner. The two half-shell-like expander element parts are provided on their two long edges, which in the assembled state are located opposite one another, with at least two lobes each formed thereon, which for the sake of mutually securing one another axially are engaged adjacent one another and are held in the radial direction on the conical end by positive adjacent engagement. The lobes are disposed on the expander element in such a manner that the expander element parts are transversely symmetrical, or when viewed in development are point-symmetrical.
In such devices, which are known from U.S. Pat. No. 4,334,813 and German laid-open application DE-OS No. 29 27 373, it has been found that where cracks or fissures have later formed in the concrete, particularly cracks or fissures 1 mm or 1.5 mm in width, these devices--that is, the outer threaded both including the half-shell-like expander element parts--either have not held or have fallen out later. Since when the outer threaded bolt slips out, the expander element parts are no longer spread apart or have slipped over the cone of the bolt, the entire device has been pulled out of the object it was being used to secure in such cases.